A5061164980- Cold Atom Physics and Bose-Einstein Condensates
- Quantum, superfluid, helium dynamics
- Graphene research and applications
- Thermal properties of materials
- Electron Spin Resonance Studies
- Thermal and Kinetic Analysis
- Thermography and Photoacoustic Techniques
- Fullerene Chemistry and Applications
- High-pressure geophysics and materials
- Thermal Radiation and Cooling Technologies
- Force Microscopy Techniques and Applications
- Advanced Thermoelectric Materials and Devices
- Acoustic Wave Resonator Technologies
- Magnetic Properties and Applications
- Spectroscopy and Quantum Chemical Studies
- Topological Materials and Phenomena
- Solid-state spectroscopy and crystallography
- Diamond and Carbon-based Materials Research
- 2D Materials and Applications
Sapienza University of Rome
2022-2025
Recent progress in understanding thermal transport complex crystals has highlighted the prominent role of heat conduction mediated by interband tunneling processes, which emerge between overlapping phonon bands (i.e., with energy differences smaller than their broadenings). These processes have recently been described different ways, relying on Wigner or Green-Kubo formalism, leading to apparently results, question definition heat-current operator. Here, we implement a full quantum approach...
The atomic motion controls important properties of materials, such as thermal transport, phase transitions, and vibrational spectra. However, simulating the ionic dynamics is exceptionally challenging when quantum fluctuations are relevant (e.g., at low temperatures or with light atoms) energy landscape anharmonic. In this paper, we present time-dependent self-consistent harmonic approximation (TDSCHA) [L. Monacelli F. Mauri, Phys. Rev. B 103, 104305 (2021)] in Wigner framework, paving way...
In crystalline materials, low lattice thermal conductivity is often associated with strong anharmonicity, which can cause significant deviations from the expected Lorentzian lineshape of phonon spectral functions. These deviations, occurring in an overdamped regime, raise questions about applicability Boltzmann transport equation. Furthermore, anharmonicity trigger structural phase transitions temperature, cannot be adequately described by standard harmonic approximation. To address these...
We show that the many-body features of graphene band structure and electronic response can be accurately evaluated by applying perturbation theory to a tight-binding (TB) model. In particular, we compare TB results for optical conductivity with previous ab-initio calculations, showing nearly perfect agreement both in low energy region near Dirac cone ($\sim 100$ meV), at higher energies {\pi} plasmon 5$ eV). A reasonable is reached also density-density Brillouin zone corner. With help...
For the large class of systems described via a time-dependent self-consistent mean field Hamiltonian including (screened) Hartree-Fock exchange, we demonstrate that any electronic linear response function allows for formulation which is variational in density matrix. To achieve our goal, consider usual form function, written terms screened and bare vertices (`bare-screen'), perform an exact rewriting purely (`screen-screen'). Within `screen-screen' formulation, can be as stationary point...
The atomic motion controls important features of materials, such as thermal transport, phase transitions, and vibrational spectra. However, the simulation ionic dynamics is exceptionally challenging when quantum fluctuations are relevant (e.g., at low temperatures or with light atoms) energy landscape anharmonic. In this work, we formulate Time-Dependent Self-Consistent Harmonic Approximation (TDSCHA) in Wigner framework, paving way for efficient computation nuclear systems sizable...